HALIFAX – The lead researcher of a new study is calling for improvements to some of Canada’s waste water treatment facilities after finding that introducing the birth control pill in waterways created a chain reaction in a lake ecosystem that nearly wiped out a freshwater fish.

The study, which is being published in Philosophical Transactions of the Royal Society B on Monday, found that introducing small amounts of estrogen into a lake led to the near extinction of the fathead minnow because it interfered with the fish’s ability to reproduce.

Lead researcher Karen Kidd of the University of New Brunswick said the study has been ongoing since the late 1990s, when researchers in the United Kingdom discovered that male fish began to develop eggs when estrogen was introduced in their habitat.